CubeRRT: CubeSat Radiometer RFI Technology Validation Mission Joel - - PowerPoint PPT Presentation

CubeRRT: CubeSat Radiometer RFI Technology Validation Mission

Joel T. Johnson, Chi-Chih Chen, C. Ball, A. O’Brien, 


• L. Garry, M. Andrews, C. McKelvey, G. Smith

The Ohio State University Sid Misra, Shannon Brown, Jonathan Kocz, Bob Jarnot NASA JPL Jeffrey Piepmeier, Jared Lucey, 
 Priscilla Mohammed, Damon Bradley, K. Horgan, 


• M. Solly

NASA GSFC NASA Earth Science Technology Forum 15 June 2016

2

RFI Problem for Microwave Radiometry

• Microwave radiometers are important Earth Observing systems for a variety
• f science applications (land, ocean, atmosphere, …)
• Observe the naturally generated microwave thermal emission from Earth

– Man-made transmissions cause radio-frequency interference (RFI)

Radiometers avoid RFI (ideally) by operating in frequency bands where transmission is prohibited

• SMAP 1% of measurements have RFI > 30K, 10% have RFI > 3K (in a

protected band!)

GMI Images at 10.7 (left) and 18.7 (right) GHz showing RFI ‘hot spots’

3

Recent Progress in Addressing RFI

• RFI problem has been recognized over many years, and ESTO has

supported technology development to make progress

– Multiple IIP’s, ACT’s, and AITT 2002-2010 developed digital backends and algorithms for radiometry to detect and filter out RFI corrupted data – Project team members collaborated throughout these programs

• Technology infused into SMAP’s L-band radiometer digital backend

currently operating successfully in space

– Project team members designed, developed, tested, and validated SMAP digital backend

• RFI problem is even more challenging for future radiometer systems

SMAP Future Number of bands 1 6 or more Bandwidth 20 MHz 100’s of MHz in each channel RFI Processing


• n ground?

Yes 
 (limited downlink volume) Not possible (downlink volume too high) RFI Processing 


• n-board spacecraft?

No; not necessary Yes; only way to address RFI challenge for future systems

4

Spectrum Allocations 6-40 GHz

• Secondary allocations of limited utility
• Current missions are operating outside protected bands and experiencing RFI

– As spectrum use increases, problem will become worse: future radiometry missions (SCLP, GPM follow on, …) may become impossible – Worst case is weak RFI that makes its way into science products

Objective Key Milestones Approach

InVEST-15-0020

CubeRRT: CubeSat Radiometer Radio Frequency Interference Technology Validation

PI: Joel T. Johnson, Ohio State University

Co-Is/Partners:

• Demonstrate wideband radio frequency interference (RFI)

mitigating backend technology for future spaceborne microwave radiometers operating 6 to 40 GHz

• Crucial to maintain US national capability for spaceborne

radiometry and associated science goals

• Demonstrate successful real-time on-board RFI detection and

mitigation in 1 GHz instantaneous bandwidth

• Demonstrate reliable cubesat mission operations, include tuning

to Earth Exploration Satellite Service (EESS) allocated bands in the 6 to 40 GHz region

• Requirements definition and system design

03/16

• Instrument engineering model subsystem tests

10/16

• Instrument engineering model integration and test

12/16

• Instrument flight model subsystem tests

04/17

• Instrument flight model integration and test

06/17

• Spacecraft integration and test

12/17

• CubeRRT launch readiness

01/18

• On-orbit operations completion

L+12 months

TRLin = 5 TRLout = 7

• C. Chen, M. Andrews, OSU; S. Misra, S. Brown, J. Kocz, R. Jarnot,

JPL; D. Bradley, P. Mohammed, J. Lucey, J. Piepmeier, GSFC

• Build upon heritage of airborne and spaceborne (SMAP) digital

backends for RFI mitigation in microwave radiometry

• Apply existing RFI mitigation strategies onboard spacecraft;

downlink additional RFI data for assessment of onboard algorithm performance

• Integrate radiometer front end, digital backend, and wideband

antenna systems into 6U CubeSat

• CSLI launch from ISS into 400 km orbit; ~ 120-300 km Earth

footprint for RFI mitigation validation

• Operate for one year at 25% duty cycle to acquire adequate

RFI data

2/16 RFI sources in Europe at 10.7 GHz

• bserved by GPM Microwave Imager

Nominal CubeRRT Configuration

6

CubeRRT Mission Properties

7

CubeRRT Development Overview

• Engineering Model (EM) development, integration, and testing

– Year 1 activity – Concludes with CDR (early 2017)

• Flight Model (FM) development, integration, and testing

– Year 2 activity – Concludes with flight ready system ready for launch (end 2017)

• Mission operations

– Year 3 activity

8

CubeRRT Development Overview

• Engineering Model (EM) development, integration, and testing

– Year 1 activity – Concludes with CDR (early 2017)

• Flight Model (FM) development, integration, and testing

– Year 2 activity – Concludes with flight ready system ready for launch (end 2017)

• Mission operations

– Year 3 activity

9

CubeRRT Subsystems and Team

• Ohio State University (OSU) lead for payload/spacecraft system

integration and test procedures

• CubeRRT payload consists of 3 subsystems:

– Radiometer Front End (RFE)

• Design, development, test by NASA Goddard Space

Flight Center (GSFC) – RF Digital Backend (RDB)

• Design, development, test by NASA Jet Propulsion

Laboratory (JPL) – Antenna (ANT)

• Design, development, test by OSU
• CubeRRT spacecraft bus (SC)

– Design, development, test by Blue Canyon Technologies (BCT)

10

RFE Block Diagram

• Antenna/reference load selector switch
• Couple noise source
• Heterodyne receiver
• Sub-harmonic Image Rejection Mixer
• IF in ADC’s second Nyquist zone (1-2 GHz)
• Control for PLO (amplitude, harmonic)
• Control fir IF: U/LSB and ampllitue

11

Noise Temperature Analysis

400 430 460 490 520 550 580 610 640 670 700 730 760 790 820 850 880 910 940 970 1000 1030 1060 1090 1120 1150 1180 1210 1240 1270 1300 1330 1360 1390 1420 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Noise Temperature (K) Frequency (GHz)

1400 K 400 K RFE only. 1 dB of cable/antenna loss adds 200-400 K

Tsys$(K) B$(MHz) tau$(s) NEDT$(K) 500 1000 0.1 0.05 500 10 0.1 0.50 500 10 1 0.16 1000 1000 0.1 0.10 1000 10 0.1 1.00 1000 10 1 0.32 2000 1000 0.1 0.20 2000 10 0.1 2.00 2000 10 1 0.63 4000 1000 0.1 0.40 4000 10 0.1 4.00 4000 10 1 1.26

12

Algorithm Summary

• The design has the

following variable parameters –

– Number of highest resolution channels – Integration time – Kurtosis threshold – CF threshold – Windowing used for CF

Cross Frequency (128ch/ 100ms) Narrowband signals Kurtosis (128-32ch/100ms) Pulsed-type/low-level RFI 128 ch

Channels combined Iterative Kurtosis and Cross- Frequency Detection 100ms Product to be integrated

64 ch 32 ch

Combined RFI flag

Combined Algorithm Combined Flags

13

CubeRRT RDB Processor

Preliminary Antenna Design

Preliminary Antenna Design


Simulated Antenna Performance

NADIR LHCP Realized Gain Reflection Coefficient

On-Orbit Configuration


Nadir Zenith

XB1 Control Unit Main Instrument Panel Deployed instrument antennas

UHF Ant (2)

Added power isolation board

Payload Components (1)


3.15” -Available cavity depth

Antenna (OSU) 3.94”L x 3.25”W x 2.22”H Working envelope

Primary Structure (BCT)

Microwave Assembly (MWA) – GSFC 3.5”L x 2.65”W x 2.6” H Working envelope Local Oscillator/ Interm Freq Assy (LOA) – GSFC 7.75”L x 4.25”W x 1.5”H Working envelope

These 2 units (the Radiometer Front End - RFE) will be integrated

• n the main

instrument panel

Payload Components (2)


Antenna envelope

Radiometer Back End (RDB)– JPL 5.0”L x 3.9”W x 1.08”H Working envelope 2 PWBs stacked

Harness Routing areas

19

Volume and Mass Margins

Item Size (U) Mass (kg)

Allocation Estimate Margin* Allocation Estimate Margin Payload Antenna

0.5 0.38 24% 0.2 0.20 0%

RFE

1 1.06

• 6%

1 1.13

• 13%

RDB

1 0.13 87% 0.4 0.20 100%

Total

2.5 1.57 59% 1.6 1.53 5%

Spacecraft

2.00

• 9.00
• Observatory Total

6 3.57 41% 14 10.53 25%

* Margin = (Allocation – Estimate)/Allocation

20

Conops

• Plan to observe at 25% duty cycle to manage battery DoD for 31 W payload
• Emphasize land observations since focus is on scenes containing RFI
• Flexible table-driven tuning of frequency to increase RFI measurements

– Developing list of known RFI sources from TRMM and JMR

• bservations (nadiral)

– Large spot size: ~ 10 seconds observation time per footprint

• Mission simulation tool developed to plan weekly observation schedule

– Algorithms for auto-planning activities under development

21

Conclusions

• CubeRRT will validate RFI detection and mitigation technologies for

future Earth observing microwave radiometers operating 6-40 GHz

• CubeRRT preliminary design completed
• EM development proceeding to payload integration and test in 


Dec 2016

22

Questions?